The present invention relates to lens forceps for extractive removal from the interior of an eye through a corneal incision of a surgically severed individual segmental lens portion or fragment, and more particularly to a lens forceps assembly formed as a manually manipulatable eye lens size clamp and a method of use thereof for such extractive removal.
U.S. Pat. No. 2,865,099 to Blackwood shows a surgical scissor instrument, having a crescent shaped member pivoted to a counterpart jamming member, and usable externally for cutting sutures sewn through the epidermis of a patient, and removing the cut strands, all in one operation. This gross instrument is inappropriate for use in sensitive, confined areas such as the interior of a human eye.
A recent innovation in ophthalmic surgery, such as in the treatment of a cataracted lens of a human eye, involves cutting the natural lens within the eye into severed portions or fragments, and removing the individual fragments through a small incision in the cornea.
Specifically, the natural lens may be cut within the eye, while still in the posterior chamber, by means of a laser or a Phaco- Emulsifier (i.e. in a straight line), or the lens may be displaced by the surgeon into the anterior chamber of the eye, and there be cut with tee aid of a surgical instrument such as a loop-snare (see U.S. Pat. No. 4,588,611 to Kelman), specially designed scissor, or similar instrument, inserted into the anterior chamber through a corneal incision. In each case, the lens is cut into two or more fragments, e.g. of segmental strip shape.
Obviously, the linear extent of the corneal incision needed to remove these cut lens strip fragments will be only a fraction of the incision length needed to remove the whole lens in one piece. Previously, when the lens as a whole was to be extracted, the surgeon could merely press the eyeball to squeeze the lens out through an appropriately large incision. In such a procedure, since the natural lens substantially fills the anterior chamber of the eye, pressure on the eyeball readily expels the lens. However, with the lens cut into several pieces, this removal method is no longer applicable.
It will be appreciated that an eye lens is of generally negligible axial thickness but has a diameter of about 10 mm, such that any corneal incision will accommodate the negligible lens thickness, whereas the incision length will depend on the particular procedure involved.
Thus, an incision length slightly exceeding 10 mm is needed to remove the whole uncut lens. On the other hand, a incision length of at most about 6 mm is needed when using a loop-snare as earlier described, e.g. to cut the lens into two half circle shaped strips, each having about a 10 mm maximum chordal width dimension (strip length), here corresponding to the diameter length, and about a 5 mm maximum arc height (strip width), here corresponding to the radial length increment along a perpendicular line, here the radius, from the midpoint (here the lens center) of the chord of cutting to the tangent point on the cut lens circumference in a line parallel to the chord.
Clearly, by utilizing an eye insertable surgical lens cutting instrument of optimal minimum cross sectional width and height dimensions, such as a loop-snare, ay increase in the incision size beyond that needed for such instrument will only be due to increased corresponding cross sectional width and height dimensions of any mechanical means employed for extractive removal of the severed lens fragments from the eye interior and/or to the cross sectional chordal width (strip length) and arc height (strip width) dimensions, as above defined, of the cut lens fragments themselves.
Understandably, any such incision in the cornea should be as small as possible to minimize injury to the eye. Accordingly, the providing of a surgical instrument and method of using the same for facilitating removal of the individual lens segmental fragments from the eye interior in connection with optimal minimum size corneal incisions otherwise needed for carrying out the above described lens cutting procedures would be highly advantageous.